Given：

Which three changes should be made to adapt this class to be used safely by multiple threads？（）

A.Compilation fails.
B.An exception is thrown at runtime.
C.The code executes and prints "running".
D.The code executes and prints "runningrunning".
E.The code executes and prints "runningrunningrunning".

A.Compilation fails.
B.An exception is thrown at runtime.
C.The code executes normally and prints "sleep".
D.The code executes normally， but nothing is printed.

A.Afoo Afoo
B.Afoo Bfoo
C.Bfoo Afoo
D.Bfoo Bfoo
E.Compilation fails